An optical gap at the fovea

A 9-year-old boy with complaints of diminution of vision and wandering movements of both eyes since birth was evaluated. His best corrected visual acuity with a refractive error of +0.50 DS/+2.00 DC at 100° in both eyes was 6/60, and intraocular pressure in both eyes was 17 mmHg. On fundus examination, a dull foveal reflex was present in both eyes. OCT showed a hyporeflective cavity just above the retinal pigment epithelium at the fovea in both eyes [Arrow, Fig. 1(a) and (b)].Figure 1: (a) and (b) Ocular Coherence Tomography of both eyes reveals hyporeflective cavity at foveaWhat would be your next step? Genetic analysis Fundus autoflourorescence OCT angiography Visual fields Illustrations– Fig. 1(a) (b) Findings – OCT of both eyes [Fig. 1 (a) and (b)] showed a hyporeflective cavity at the fovea suggesting loss of the ellipsoid zone of photoreceptors. This finding along with the presence of nystagmus since birth and hyperopic refractive error was suggestive of cone dystrophy, which was further confirmed by genetic analysis. Diagnosis – Achromatopsia Correct answer – (A) Genetic analysis: On genetic testing, the patient was found to have a mutation in the CNGA3 gene with c. 1279C > T (p.Arg427Cys) and c. 822G > T (p.Arg274Ser) variants. The patient was advised photochromatic tinted glasses, low-vision aids, and genetic counseling. Genetic testing is an essential part of clinical care for patients affected with IRDs as it helps to confirm the diagnosis, understand the inheritance of the condition, and determine eligibility for gene-specific treatments or clinical trials. Knowing the inheritance can help in counseling the patient as well as the parents. Discussion Achromatopsia is a rare autosomal recessive disorder with an incidence of roughly 1 in 30,000.[1] OCT shows a hyporeflective “optical gap” at the fovea corresponding to foveal loss of photoreceptor outer segments. This finding can be seen in Stargardt’s disease, occult macular dystrophy, and other cone dystrophies.[2] Mutation in CNGA3 and CNGB3 genes, which encode the alpha and beta subunits of cone cyclic-GMP gated cation channels, respectively, are found in the majority of cases of achromatopsia, ATF6, GNAT2, PDE6C, and PDE6H are also found in a few cases of achromatopsia.[3] Although clinical trials are going on, currently, there is no treatment available for achromatopsia. Low-vision aids, genetic counseling, refractive error correction, and tinted glasses for photophobia can be given for the management of symptoms. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship: Nil. Conflicts of interest: There are no conflicts of interest.